Field
The invention generally relates to processes for reducing condensation in an acid gas scrubbing tower useful for upgrading a hydrocarbon-containing stream, such as hydrocarbon streams containing C2+ mono-olefins, diolefin, and one or more acidic gases, equipment useful in such processes, and upgraded process streams produced using the same.
Description of Related Art
Olefins can be used to produce many useful products. For example, ethylene and/or propylene can be polymerized to produce polymer, such as polyethylene, polypropylene, ethylene-propylene copolymer, etc. Olefins can be produced by many conventional processes, including: (1) catalytically converting alcohol, such as methanol; (2) pyrolysing a hydrocarbon-containing feed, as in steam cracking; or (3) catalytically cracking a hydrocarbon feed, as in fluidized catalytic cracking, hydrocracking, etc. Besides olefins, effluents from these processes can contain acidic gases, e.g., H2S, CO2, etc. When the feeds to these processes contain sulfur and/or sulfur-containing molecules, such as in the catalytic cracking and/or steam cracking of heavy oil and/or one or more fractions thereof, the acidic gases generally include H2S. The effluent can also contain diolefin molecules, for example, propadiene, cyclopentadiene, isoprene, or butadiene. This is especially true when steam cracking is utilized for producing the olefins.
It is conventional to utilize amine and/or caustic for removing one or more acidic gases from a process stream containing olefins. For example, CO2 and H2S can be removed from a steam cracker effluent by contacting the effluent with a caustic and/or amine scrubbing solution, e.g., by an acid gas scrubbing process in caustic or amine scrubbing towers.
The amine scrubbing solution absorbs the acid gases like CO2 and H2S and removes them from the olefins process stream. The scrubbing solution containing the acid gases exits the scrubbing tower and is conducted to an amine regeneration system where the solution is heated to release the acid gases. The scrubbing solution exiting the regeneration system, mostly free of acid gases, is returned to the scrubbing tower.
In a caustic scrubbing tower, the acid gases such as CO2 and H2S are absorbed and react in the caustic scrubbing solution to form caustic salts and water. The caustic scrubbing solution is recirculated by pumps through the caustic tower. The caustic salts are removed from the circulating scrubbing solution in a spent caustic stream for disposal while a fresh caustic stream is added to maintain an optimal caustic scrubbing solution.
A significant hurdle to operation of acid gas scrubbing process, e.g., caustic or amine scrubbing towers, is buildup of polymerized foulant. Polymerization fouling can cause the acid gas scrubbing system to limit capacity for the broader olefin production process resulting in significant negative financial impact. An improved process is therefore desired which reduces the buildup of polymerized foulant in the acid gas scrubbing system.